There has been a considerable demand for "soft-serve" ice cream, that is extruded out of a nozzle at about 18 degrees F., as opposed to "hard" ice cream at about 8 degrees F. Soft ice cream is actually more tasty than the similar "dip-serve" hard product because it does not freeze and numb the taste buds as much.
Unfortunately, the best equipment that is most commonly used for the "soft-serve" product is expensive; it is actually a batch-freezer (or ice cream machine) which is used to make the basic ice cream, that is subsequently hardened in a deep-freezer. Such machine has an agitator chamber and a refrigerator, and it serves usually one flavor. Soft ice cream spoils much faster than hard ice cream, and the consistency becomes gummy. These machines should be dumped out, and cleaned every night. Only high volume establishments can afford to buy and operate these machines.
For these reasons, there have been attempts to introduce low cost machines that convert hard ice cream to soft ice cream by single servings. There are a number of other very significant advantages of this process, that are obvious to those skilled in the art, namely: the flavoring can be introduced into a vanilla, chocolate, or unflavored ice cream base, at the hard to soft conversion process, thereby greatly reducing the storage facility requirements for various flavors. A fresh product is obtained even for the "low" demand flavors, while hundreds of flavor combinations become practical to make!
There are a number of machines on the market that soften, mix, chop, and extrude the ice cream product. All of them are substantially improvements on a conical auger type apparatus patented by C A Reed, (U.S. Pat. No. 2,626,133; January 1953). These machines have not been very popular for a number of reasons, not the least of these were their complexity and cost. It is most unfortunate since it puts out an excellent product, particularly the cookie additions are unsurpassed since they are fresh and crisp, not soggy as in hard ice cream.
In the last few years, however, there has been an increased interest in these machines, to serve frozen yoghurt dessert, and to mix and chop fresh fruits, nuts, cookies, and candy, into the product. The fruit aggregate additions are soft and tasty, not frozen (icy), as in ordinary fruit ice cream.